The present invention provides a much needed tool for assisting radiologists and others involved in the field of radiology in understanding computed radiography and in helping computed radiography achieve its full potential.
The use of x-ray imaging apparatus, known as the field of radiology, has been used for many decades; in assisting medical professionals in diagnosing and understanding features internal to the human body. In conventional x-ray radiology, the portion of the patient's body to be examined is interposed between an x-ray radiation source and an unexposed photographic film. The x-rays pass through the patient's body, subject to variable absorption by the varying body parts. The resulting modified x-ray beam exposes the film in a pattern which illustrates internal organs of the patient's body. Bones, of course, absorb more radiation than soft body tissues, and there is variability in the absorption of the x-rays by the various tissue components. This variability is what gives rise to the perceivable image on the film. In conventional x-ray radiology, the photographic film has a chemical emulsion which is developed using conventional chemical processing techniques. That chemical processing technique used in development of the film usually does not vary from one x-ray exposure to another.
In the past ten years or so a new form of radiology has begun to gain acceptance, namely computed radiography. In computed radiography, the film with its chemical emulsion is replaced by a plate having phosphors which are selectively and temporarily altered by the x-ray beam that has passed through the patient. The phosphors are then "read" to provide a digital data record, instead of a film emulsion record. Machines of this type are sold by Fuji Medical Systems USA, Inc., Stamford Conn., USA under the designation FCR.TM., by Siemens Medical Systems, Inc. of Iselin, N.J. under the name Digiscan and other manufacturers under various trademarks.
The digital data record can be manipulated using digital data processing techniques, and a visible display can be created on any of several media. The digital processing usually has the objective of enhancing the usefulness of the visual display. A primary digital processing technique, which is virtually universally performed, is an exposure correction routine. The computer evaluates the amount of exposure over the entire image to determine an average black or white value for the image and then adds or subtracts from all of the pixel elements of image to achieve an acceptable image density.
While computed radiography has achieved considerable acceptance, there is still resistance on the part of many radiologists to the use of this new technology. The images created by computed radiography can be fully as illustrative of the patient's conditions as the conventional x-ray film, but will, in many cases have a somewhat different appearance. Radiologists are intensively trained in reading x-ray images made on the conventional film to perceive images and features which the layperson with an untrained eye simply does not see or would not notice without having it pointed out by the trained radiologist. Radiologists used to discerning such fine differences find the different overall appearance of computed radiography images to be so different that they do not have confidence that they can properly read these images, despite the fact that the computed radiography image generally shows all the detail of the x-ray film image. Thus, there is a need in the art for a means to familiarize radiologists with the capabilities of computed radiography and to permit them to gain confidence in the images produced by computed radiography to the level they are already comfortable with for film x-rays.
In addition, one of the important advantages of computed radiography is the fact that the data, being stored in digital form, can be transmitted by a digital data transmission network, whether that be within a hospital or to a remote location over telephone or other transmission lines. Transmission of images in a Picture Archiving and Communication Systems (known by the acronym PACS) over relatively short distances is commonly referred to as a Local Area Network (LAN); distribution of images over a larger distance is usually called a Wide Area Network (WAN); and transmission of images to a remote site is usually called teleradiology. A PACS network can encompass one or more of these image transfer modalities. Computed radiography images can be incorporated into each of these networking systems. By storing and archiving computed radiography images, these images become part of a PACS. The Surgeon General of the military services implemented such a PACS known the Medical Diagnostic Imaging Support (MDIS).
Features of the MDIS include intra-hospital PACS networks which make use of high-speed communication protocol to support high volume image areas such as the radiology department and other selected patient areas such as the hospital emergency room. Hospitals in the military services network are linked by teleradiology systems to permit transmission of data throughout the network, as needed. This enables a hospital to use the services of a remote radiologist to read the computed radiography image, without necessitating travel by the radiologist to the patient's site.
However, radiologists remote from the x-ray exposure facilities may feel reticence about reading the images created from the transmitted digital data, stemming from uncertainty about the quality of the procedures used in making the images or a lack of familiarity with the precise techniques used by the imaging facility. Accordingly, there is a need in the art for a means and method to provide standardization of computed radiography image quality for LAN, WAN, teleradiology and other transmissions of radiographic digital data.